Sodium-dependent glucose cotransporters (SGLTs) play a key role in maintaining human plasma glucose stable. SGLTs have been found in intestine (SGLT1) and kidney (SGLT1 and SGLT2). Renal SGLT reabsorbs glucose from the renal filtrate, thereby preventing the loss of glucose from urine. 98% of glucose is reabsorbed in the kidney by SGLT2, and only the remaining 2% is reabsorbed by SGLT1. Inhibition of SGLT2 can specifically inhibit the reabsorption of glucose by kidney and increase the excretion of glucose in the urine, which may normalize the plasma glucose for diabetics. Therefore, the inhibitors of SGLT, particularly SGLT2, are promising candidates for antidiabetic drugs (Handlon, A. L., Expert Opin. Ther. Patents (2005) 15 (11):1531-1540).
So far, a lot of pharmaceutical companies have developed a series of SGLT2 inhibitors, such as those described in: Handlon, A. L., Expert Opin. Ther. Patents (2005) 15 (11):1531-1540; William N. W., Journal of Medicinal Chemistry, 2009, Vol. 52, No. 7, 1785-1794; Chao, E. C. et al., Nature Reviews Drug Discovery, 2010, Vol. 9, No. 7, 551-559. Aryl glycosides as SGLT2 inhibitors are also known by the following patent applications: WO 01/27128, WO 02/083066, WO 03/099836, US 2003/0114390, WO 04/063209, WO 2005/012326, US 2005/0209166, US 2006/0122126, WO 2006/011502, US 2007/0293690, WO 2008/034859, WO 2008/122014 and WO 2009/026537.